Crosslinking compositions and coatings formed therefrom

ABSTRACT

A crosslinking composition includes a compound having at least two functional groups that are each independently represented by Chemical Structure (I):X is an oxygen, sulfur, or nitrogen; R1 is an alkyl group, an aryl group, or an alkylaryl group; R2, R3, and R4 are each independently an alkyl group, an aryl group, an alkylaryl group, or a hydrogen; R5 is an alkyl group, an aryl group, an alkylaryl group, or a hydrogen; z is 0 when X is oxygen or sulfur and z is 1 when X is nitrogen; and when a double bond is formed between a carbon atom bonded to R3 and an adjacent nitrogen, m is 0, and when a single bond is formed between the carbon atom bonded to R3 and the adjacent nitrogen, m is 1.

FIELD OF THE INVENTION

The present invention relates to crosslinking compositions and coatingsformed therefrom.

BACKGROUND OF THE INVENTION

Crosslinking compositions contain one or more components that arecapable of reacting and crosslinking to form coating layers and films.For instance, crosslinking compositions are commonly applied tosubstrates to form coatings that provide numerous properties includingprotective properties, decorative properties, and the like. Thesecoatings are typically prepared from compositions that containself-crosslinking compounds, and/or film-forming resins and crosslinkersthat react with the film-forming resins. Due to their reactivity andability to form high-performance coatings, isocyanate functionalcompounds are often used to form such coatings. However, isocyanatespresent health risks including irritation to skin and mucous membranesas well as environmental concerns. Thus, it is desirable to providealternatives to isocyanates that can be used to form high-performancecoatings.

SUMMARY OF THE INVENTION

The present invention relates to a crosslinking composition comprising acompound comprising at least two functional groups that are eachindependently represented by Chemical Structure (I):

With respect to Chemical Structure (I), X is an oxygen, sulfur, ornitrogen; R¹ is an alkyl group, an aryl group, or an alkylaryl group;R², R³, and R⁴ are each independently an alkyl group, an aryl group, analkylaryl group, or a hydrogen; R⁵ is an alkyl group, an aryl group, analkylaryl group, or a hydrogen; z is 0 when X is oxygen or sulfur and zis 1 when X is nitrogen; and when a double bond is formed between acarbon atom bonded to R³ and an adjacent nitrogen, m is 0, and when asingle bond is formed between the carbon atom bonded to R³ and theadjacent nitrogen, m is 1. Further, (i) the compound comprises one ormore additional functional groups that are reactive with the functionalgroups represented by Chemical Structure (I) such that the compound isself-crosslinkable; and/or (ii) the composition further comprises afilm-forming resin comprising functional groups that are reactive withthe functional groups represented by Chemical Structure (I) of thecompound.

The present invention also relates to a coating formed from thecrosslinking composition and substrates at least partially coated withthe coating.

DESCRIPTION OF THE INVENTION

For purposes of the following detailed description, it is to beunderstood that the invention may assume various alternative variationsand step sequences, except where expressly specified to the contrary.Moreover, other than in any operating examples, or where otherwiseindicated, all numbers expressing, for example, quantities ofingredients used in the specification and claims are to be understood asbeing modified in all instances by the term “about”. Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties to be obtained by the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard variation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

In this application, the use of the singular includes the plural andplural encompasses singular, unless specifically stated otherwise. Inaddition, in this application, the use of “or” means “and/or” unlessspecifically stated otherwise, even though “and/or” may be explicitlyused in certain instances. Further, in this application, the use of “a”or “an” means “at least one” unless specifically stated otherwise. Forexample, “a” compound, “a” film-forming resin, and the like refer to oneor more of any of these items.

As indicated, the present invention relates to a crosslinkingcomposition comprising a compound comprising at least two functionalgroups that are each independently represented by Chemical Structure(I):

With respect to Chemical Structure (I), X is an oxygen, sulfur, ornitrogen; R¹ is an alkyl group, an aryl group, or an alkylaryl group;R², R³, and R⁴ are each independently an alkyl group, an aryl group, analkylaryl group, or a hydrogen; R⁵ is an alkyl group, an aryl group, analkylaryl group, or a hydrogen; z is 0 (i.e. there is no R⁵) when X isoxygen or sulfur and z is 1 when X is nitrogen; and when a double bondis formed between the carbon atom bonded to R³ and the adjacentnitrogen, m is 0, and when a single bond is formed between the carbonatom bonded to R³ and the adjacent nitrogen, m is 1.

As used herein, an “alkyl group” refers to a linear, branched, and/orcyclic monovalent, saturated hydrocarbon radical. The alkyl group mayinclude, but is not limited to, a linear or branched C₁-C₃₀ monovalenthydrocarbon radical, or a linear or branched C₁-C₂₀ monovalenthydrocarbon radical, or a linear or branched C₁-C₁₀ monovalenthydrocarbon radical, or a linear or branched C₁ to C₆ monovalenthydrocarbon radical, or a linear or branched C₁ to C₄ monovalenthydrocarbon radical, such as methyl or ethyl. The alkyl group may alsoinclude, but is not limited to, a cyclic C₃-C₁₉ monovalent hydrocarbonradical, or a cyclic C₃-C₁₂ monovalent hydrocarbon radical, or a cyclicC₅-C₇ monovalent hydrocarbon radical. Further, the alkyl group canoptionally comprise an interrupting heteroatom, functional group, or acombination thereof. For example, the alkyl group can be interrupted by:(i) a heteroatom including, but not limited to, an oxygen atom, anitrogen atom, a sulfur atom, or a combination thereof; and/or (ii) afunctional group including, but not limited to, an ester group, an ethergroup, a carbonyl group, an amide group, an amino group, or combinationsthereof. Alternatively, the alkyl group can be free of interruptingheteroatoms and/or functional groups.

The term “linear” refers to a compound having a straight hydrocarbonchain, the term “branched” refers to a compound having a hydrocarbonchain with a hydrogen replaced by a substituent such as an alkyl groupthat branches or extends out from a straight chain, and the term“cyclic” refers to a closed ring structure. The cyclic groups alsoencompass bridged ring polycycloalkyl groups (or bridged ring polycyclicgroups) and fused ring polycycloalkyl groups (or fused ring polycyclicgroups).

As used herein, an “aryl group” refers to a substituent derived from anaromatic ring, such as a phenyl group for example. The aryl group can bederived from a monocyclic aromatic ring, a bicyclic aromatic ring, or apolycyclic aromatic ring. The aryl group can also include a heteroarylgroup in which at least one carbon atom of the aromatic group isreplaced by a heteroatom such as nitrogen, oxygen, sulfur, or acombination thereof. The aryl group can also include a substituted arylgroup where at least one hydrogen thereof has been optionally replacedor substituted with a group that is other than hydrogen.

As used herein, the term “aromatic” refers to a cyclically conjugatedhydrocarbon with a stability (due to delocalization) that issignificantly greater than that of a hypothetical localized structure.

An “alkylaryl group” refers to alkyl-substituted aryl group. That is, analkylaryl group, as used herein, is a substituent derived from anaromatic ring and which is substituted with a linear, branched, and/orcyclic monovalent, saturated hydrocarbon.

The alkyl group, aryl group, or alkylaryl group of R¹ and the nitrogen,sulfur, or oxygen of X can act as a cleavable blocking group that isremoved upon exposure to a minimum temperature. As such, upon exposureto a minimum temperature, the alkyl group, aryl group, or alkylarylgroup of R¹ and the nitrogen, sulfur, or oxygen of X are removed orcleaved, thereby allowing for additional reactions. The alkyl group,aryl group, or alkylaryl group of R¹ and the nitrogen, sulfur, or oxygenof X can be removed at a temperature of at least 60° C., at least 80°C., at least 100° C., at least 120° C., at least 140° C., or at least160° C.

As indicated, when a double bond is formed between the carbon atombonded to R³ and the adjacent nitrogen, m is 0. The resulting functionalgroup can be represented by Chemical Structure (II):

Alternatively, when a single bond is formed between the carbon atombonded to R³ and the adjacent nitrogen, m is 1. The resulting functionalgroup can be represented by Chemical Structure (III):

As indicated, the compound of the present invention comprises at leasttwo functional groups, such as at least three functional groups or atleast four functional groups, represented by Chemical Structure (I). Thefunctional groups can comprise any combination of functional groupsrepresented by Chemical Structure (I). For instance, the compound cancomprise one or more functional groups represented by Chemical Structure(II), which is derived from Chemical Structure (I), and one or morefunctional groups represented by Chemical Structure (III), which is alsoderived from Chemical Structure (I).

The previously described compound can also comprise additionalfunctional groups. Non-limiting examples of additional functional groupsinclude hydroxyl groups, thiol groups, carboxylic acid groups, aminegroups, epoxide groups, carbamate groups, amide groups, urea groups,isocyanate groups (including blocked isocyanate groups), andcombinations thereof. The compound can also be free of any of theadditional functional groups

The compound can comprise various linkages that form the backbone and/orother structural portions, such as pendant groups or chains, of thechemical compound. Non-limiting examples of linkages include esterlinkages, ether linkages, aromatic groups, or a combination thereof. Assuch, the compound of the present invention can comprise: (i) at leasttwo functional groups represented by Chemical Structure (I); (ii) esterlinkages, ether linkages, aromatic groups, or a combination thereof, forexample; and optionally (iii) additional functional groups differentfrom the functional groups represented by Chemical Structure (I).

The compound of the present invention can comprise a monomer thatcontains the functional groups represented by Chemical Structure (I), ora polymer that contains the functional groups represented by ChemicalStructure (I). It is appreciated that the composition of the presentinvention can comprise a monomer and a polymer that both have functionalgroups represented by Chemical Structure (I).

As used herein, the term polymer refers to oligomers, homopolymers(e.g., prepared from a single monomer species), copolymers (e.g.,prepared from at least two monomer species), terpolymers (e.g., preparedfrom at least three monomer species), and graft polymers. The term“resin” is used interchangeably with the term “polymer”.

When the compound is a polymer, the functional groups represented byChemical Structure (I) can form a pendant and/or terminal group on thepolymer. A “pendant group,” also referred to as a “side chain”, is anoffshoot from the polymer main chain and is not part of the main chain,and a “terminal group” refers to a functional group positioned at theend of the polymer main chain.

Further, when the compound is a polymer, it is appreciated that thecompound can comprise various types of polymers provided that thepolymer has two or more functional groups represented by ChemicalStructure (I). Non-limiting examples of polymers that can form thecompound include (meth)acrylate resins, polyurethanes, polyesters,polyamides, polyethers, polysiloxanes, epoxy resins, vinyl resins,copolymers thereof, and combinations thereof, and which comprise two ormore functional groups represented by Chemical Structure (I). Forinstance, the compound can comprise a (meth)acrylate resin (i.e. anaddition polymer derived from one or more monomers comprising(meth)acrylate groups) that comprises two or more functional groupsrepresented by Chemical Structure (I). The term “(meth)acrylate” refersto the “methacrylate” and the “acrylate”.

Various reactants can be used to obtain the compound of the presentinvention. The reactants can be chosen to provide a particular structurehaving certain linkages and, optionally, additional functional groupsthat are different from the functional groups represented by ChemicalStructure (I). For example, the compound can be formed from reactantscomprising: (i) a reaction product of: (a) a mono-aldo or ketofunctional compound comprising a hydroxyl functional group, an aminofunctional group, a thiol functional group, a carboxylic acid functionalgroup, or any combination thereof; and (b) a hydrazide or hydrazonecomprising a group represented by —XR¹(R⁵)_(z) that is attached to acarbon atom of the hydrazide or hydrazone, in which R¹ is an alkylgroup, an aryl group, or an alkylaryl group; X is an oxygen, sulfur, ornitrogen; R⁵ is an alkyl group, an aryl group, an alkylaryl group, or ahydrogen; z is 0 when X is oxygen or sulfur and z is 1 when X isnitrogen; and (ii) a component comprising two or more functional groupsreactive with the hydroxyl functional group, the amino functional group,the thiol functional group, and/or the carboxylic acid functional groupof the resulting reaction product of (i).

As used herein, a “mono-aldo or keto functional compound” refers to acompound that has only one aldo (aldehyde) or keto (ketone) functionalgroup. As indicated, the mono-aldo or keto functional compound alsocomprises one or more functional groups selected from a hydroxylfunctional group, an amino functional group, a thiol functional group,and a carboxylic acid functional group including combinations of suchfunctional groups. Non-limiting examples of suitable mono-aldo or ketofunctional compounds include hydroxyacetophenone, hydroxybenzaldehyde,thioacetophenone, thiobenzaldehyde, amino acetophenone,aminobenzaldehyde, acetylbenzaldehyde, levulinic acid, and combinationsthereof.

Further, a “hydrazide” refers to a compound comprising a hydrazidefunctional group, and a “hydrazone” refers to a compound comprising ahydrazone functional group. It is appreciated that the hydrazides andhydrazones comprise reactive amino functional groups. As previouslydescribed, the hydrazide and hydrazone also comprises a grouprepresented by —XR¹(R⁵)_(z) that is attached to a carbon atom of thehydrazide or hydrazone. Non-limiting examples of the previouslydescribed hydrazide and hydrazone components include carbazates,semicarbazides, carbazides, hydrazinecarbothioates, and combinationsthereof.

It is appreciated that the aldo or keto functional group will react withthe hydrazide or hydrazone functional group. The resulting reactionproduct will include one or more functional groups selected from ahydroxyl functional group, an amino functional group, a carboxylic acidfunctional group, and a thiol functional group as well as the grouprepresented by —XR¹(R⁵)_(z).

The resulting reaction product previously described is further reactedwith the two or more functional groups of component (ii). Particularly,the hydroxyl functional group, the amino functional group, thecarboxylic acid functional group, and/or the thiol functional group ofthe reaction product of (i) is reacted with the two or more functionalgroups of component (ii) to form the compound of the present invention.

Component (ii) can be selected from various monomers and polymersprovided that the monomers and polymers comprise two or more functionalgroups that are reactive with the hydroxyl functional group, the aminofunctional group, the thiol functional group, and/or the carboxylic acidfunctional group of the reaction product of (i). Non-limiting examplesof functional groups reactive with the hydroxyl functional group, theamino functional group, the thiol functional group, and/or thecarboxylic acid functional group of the reaction product of (i) includeepoxy functional groups, ethylenically unsaturated groups such as(meth)acrylates, maleimides, alkyl and aryl halides, mesylates,tosylates, esters, nitriles, amides, and combinations thereof. It isappreciated that the monomer or polymer that forms component (ii) can beselected to provide certain linkages and, optionally, additionalfunctional groups including, but not limited to, the linkages andadditional functional groups previously described.

As previously described, when component (ii) is a polymer, component(ii) can comprise various types of polymers provided that the polymerhas two or more functional groups that are reactive with the hydroxylfunctional group, the amino functional group, the thiol functionalgroup, and the carboxylic acid functional group of the reaction productof (i) as previously described. Non-limiting examples of polymers thatcan form component (ii) include any of the polymers previously describedbut which comprise two or more functional groups that are reactive withthe hydroxyl functional group, the amino functional group, the thiolfunctional group, and/or the carboxylic acid functional group of thereaction product of (i). For instance, the compound can comprise a(meth)acrylate resin that comprises two or more functional groups thatare reactive with the hydroxyl functional group, the amino functionalgroup, the carboxylic acid functional group, and/or the thiol functionalgroup of the reaction product of (i), such as epoxy functional groupsfor example. Further, the two or more functional groups reactive withthe hydroxyl functional group, the amino functional group, thecarboxylic acid functional group, and/or the thiol functional group ofthe reaction product of (i) can be pendant groups and/or terminal groupson the polymer.

The compound of the present can also be prepared with differentreactants. For example, the compound can be obtained by reacting (i) ahydrazide or hydrazone comprising a group represented by —XR¹(R⁵)_(z)that is attached to a carbon atom of the hydrazide or hydrazone, inwhich R¹ is an alkyl group, an aryl group, or an alkylaryl group and Xis an oxygen, sulfur, or nitrogen; R⁵ is an alkyl group, an aryl group,an alkylaryl group, or a hydrogen; z is 0 when X is oxygen or sulfur andz is 1 when X is nitrogen; and (ii) a component comprising two or morefunctional groups reactive with an amino group (i.e. primary aminogroup) of the hydrazide or hydrazone functionality of (i).

The hydrazide or hydrazone can comprise any of the previously describedhydrazides or hydrazones comprising a group represented by —XR¹(R⁵)_(z).Component (ii) can be selected from various monomers and polymersprovided that the monomers and polymers comprise two or more functionalgroups that are reactive with the hydrazide or hydrazone functionalityof (i). Non-limiting examples of functional groups reactive with thehydrazide or hydrazone functionality of (i) include ethylenicallyunsaturated functional groups, keto functional groups, aldo functionalgroups, epoxy functional groups, or any combination thereof. As usedherein, “ethylenically unsaturated” refers to a group having at leastone carbon-carbon double bond. Non-limiting examples of ethylenicallyunsaturated groups include, but are not limited to, (meth)acrylategroups, vinyl groups, and combinations thereof. It is appreciated thatthe monomer or polymer that forms component (ii) can be selected toprovide certain linkages and, optionally, additional functional groupsincluding any of the linkages and additional functional groupspreviously described, for example.

As previously described, when component (ii) is a polymer, component(ii) can comprise various types of polymers provided that the polymerhas two or more functional groups that are reactive with the hydrazideor hydrazone functionality of (i) as previously described. Non-limitingexamples of polymers that can form component (ii) include any of thepolymers previously described but which comprise two or more functionalgroups that are reactive with the hydrazide or hydrazone functionalityof (i). For instance, the compound can comprise a (meth)acrylate resinthat comprises two or more functional groups that are reactive with thehydrazide or hydrazone functionality of (i), such as aldo and/or(meth)acrylate functional groups for example. Another non-limitingexample is an epoxy functional acrylic resin that is first reacted witha carboxylic acid compound comprising a keto or aldo-functional group,such as levulinic acid, to add keto or aldo-functional groups on theacrylic resin prior to the reaction with the hydrazide or hydrazonefunctionality of (i). Further, the two or more functional groups thatare reactive with the hydrazide or hydrazone functionality of (i) can bependant groups and/or terminal groups on the polymer.

The previously described reactants and reaction products that form thecompound of the present invention can be mixed and reacted in a liquidmedium such as a non-aqueous medium and optionally in the presence of acatalyst such as in the presence of an amine catalyst. As used herein,the term “non-aqueous” refers to a liquid medium comprising less than 50weight % water, based on the total weight of the liquid medium. Inaccordance with the present invention, such non-aqueous liquid mediumscan comprise less than 40 weight % water, or less than 30 weight %water, or less than 20 weight % water, or less than 10 weight % water,or less than 5 weight % water, based on the total weight of the liquidmedium. The solvents that make up more than 50 weight % and optionallyup to 100 weight % of the liquid medium include organic solvents.Non-limiting examples of suitable organic solvents include polar organicsolvents e.g. protic organic solvents such as glycols, glycol etheralcohols, alcohols; and aprotic organic solvents such as ketones, glycoldiethers, esters, and diesters. Other non-limiting examples of organicsolvents include non-polar solvents such as aromatic and aliphatichydrocarbons.

The compound of the present invention can comprise at least 5 weight %,at least 10 weight %, at least 20 weight %, at least 40 weight %, or atleast 60 weight % of the coating composition, based on the total solidsweight of the coating composition. The compound of the present inventioncan comprise up to 100 weight %, up to 90 weight %, up to 80 weight %,or up to 70 weight % of the coating composition, based on the totalsolids weight of the coating composition. The compound of the presentinvention can include an amount with range such as, for example, of from5 weight % to 100 weight %, or from 10 weight % to 90 weight %, or from20 weight % to 80 weight % of the coating composition, based on thetotal solids weight of the coating composition.

As previously described, the compound can comprise one or moreadditional functional groups. These additional functional groups can beselected from functional groups that are reactive with the functionalgroups represented by Chemical Structure (I) such that the compound isself-crosslinkable. As used herein, the term “self-crosslinkable” refersto a compound comprising two or more functional groups that are reactivewith each other and which participate in intramolecular and/orintermolecular crosslinking reactions to form a covalent linkage in theabsence of other external reactive compounds. For instance, the compoundof the present invention can also comprise hydroxyl functional groups,amino functional groups, thiol functional groups, and any combinationthereof that are reactive with the functional groups represented byChemical Structure (I).

The compound of the present invention can also be free of additionalfunctional groups that are reactive with the functional groupsrepresented by Chemical Structure (I) such that the compound isnon-self-crosslinkable. As used herein, “non-self-crosslinkable” refersto a compound comprising one or more functional groups that are notreactive with each other and which thus requires one or more externalcompounds reactive therewith to undergo a crosslinking reaction.

When the crosslinking composition of the present invention contains thepreviously described non-self-crosslinkable compound, the compositionfurther comprises a film-forming resin having functional groups reactivewith the functional groups represented by Chemical Structure (I) of thenon-self-crosslinkable compound. As used herein, a “film-forming resin”refers to a resin that can form a self-supporting continuous film on atleast a horizontal surface of a substrate upon removal of any diluentsor carriers present in the composition and/or upon curing.

Non-limiting examples of suitable film-forming resins include(meth)acrylate resins, polyurethanes, polyesters, polyamides,polyethers, polysiloxanes, epoxy resins, vinyl resins, copolymersthereof, and combinations thereof. Further, the film-forming resinscomprise functional groups that are reactive with the functional groupsrepresented by Chemical Structure (I) of the compound. Non-limitingexamples of such functional groups include hydroxyl functional groups,amino functional groups, thiol functional groups, and any combinationthereof. The film-forming resins can also include additional functionalgroups such as, for example, carboxylic acid groups, epoxide groups,carbamate groups, amide groups, urea groups, isocyanate groups(including blocked isocyanate groups), and combinations thereof.

The film-forming resin used with the present invention can also comprisean equivalent weight of 400 or less, or 300 or less, or 250 or less, or200 or less, or 180 or less, or 150 or less. As used herein, “equivalentweight” refers to the average weight molecular weight of a resin dividedby the number of functional groups. Further, the average weightmolecular weight is determined by gel permeation chromatography relativeto linear polystyrene standards of 800 to 900,000 Daltons as measuredwith a Waters 2695 separation module with a Waters 410 differentialrefractometer (RI detector). Tetrahydrofuran (THF) is used as the eluentat a flow rate of 1 ml min-1, and two PLgel Mixed-C (300×7.5 mm) columnsis used for separation.

It is appreciated that the previously described compound can act as acrosslinker that reacts with the film-forming resin during cure to forma coating layer as explained in more detail below. As used herein, theterm “crosslinker” refers to a molecule comprising two or morefunctional groups that are reactive with other functional groups andthat is capable of linking two or more monomers or polymers throughchemical bonds.

When included in the composition, the film-forming resin reactive withthe functional groups represented by Chemical Structure (I) of thecompound can comprise at least 5 weight %, at least 10 weight %, atleast 20 weight %, at least 40 weight %, or at least 60 weight % of thecoating composition, based on the total solids weight of the coatingcomposition. The film-forming resin can comprise up to 95 weight %, upto 90 weight %, up to 80 weight %, or up to 70 weight % of the coatingcomposition, based on the total solids weight of the coatingcomposition. The film-forming resin of the present invention can includean amount within a range such as, for example, of from 5 weight % to 95weight %, or from 10 weight % to 90 weight %, or from 20 weight % to 80weight % of the coating composition, based on the total solids weight ofthe coating composition.

It is appreciated that a film-forming resin can also be added to thecrosslinking composition that comprises the compound that isself-crosslinkable. The film-forming resin can be reactive withadditional functional groups on the compound and/or the functionalgroups represented by Chemical Structure (I) such that the compound isreactive with itself and additional film-forming resins. Thecrosslinking composition that comprises the compound that isself-crosslinkable can also be free of such film-forming resins that arereactive with the self-crosslinkable compound.

The crosslinking composition of the present invention can also includeboth the previously described compound that is self-crosslinkable andthe previously described compound that is non-self-crosslinkable. Suchcrosslinking compositions can also comprise a film-forming resin that isreactive with the self-crosslinkable and/or non-self-crosslinkablecompounds. Alternatively, the crosslinking composition can be free of afilm-forming resin that is reactive with the self-crosslinkable and/ornon-self-crosslinkable compounds.

The crosslinking composition can also comprise additional components.For example, the coating composition can also comprise additionalfilm-forming resins that are not reactive with the previously describedself-crosslinkable and/or non-self-crosslinkable compounds. Theadditional resins can include any of a variety of thermoplastic and/orthermosetting resins known in the art. As used herein, the term“thermosetting” refers to resins that “set” irreversibly upon curing orcrosslinking, wherein the polymer chains are joined together by covalentbonds. Once cured, a thermosetting resin will not melt upon theapplication of heat and is insoluble in solvents. As noted, theadditional resins can also include a thermoplastic resin. As usedherein, the term “thermoplastic” refers to resins that include polymericcomponents that are not joined by covalent bonds and, thereby, canundergo liquid flow upon heating.

The additional resins can be selected from various types of resinsprovided that the resins do not have functional groups that are reactivewith the functional groups of the self-crosslinkable and/ornon-self-crosslinkable compounds. For example, the additional resins canbe selected from any of the resins previously described provided thatthe resins do not have functional groups that are reactive with thefunctional groups of the self-crosslinkable and/ornon-self-crosslinkable compounds.

Compositions containing thermosetting resins are typically reacted witha crosslinker. As such, when additional film-forming resins are used inthe crosslinking composition, the composition can comprise additionalcrosslinkers that are reactive with the additional film-forming resins.The thermosetting resins can also have functional groups that arereactive with themselves such that the additional resin isself-crosslinking.

Non-limiting examples of additional crosslinkers include polyhydrazides,carbodiimides, polyols, phenolic resins, epoxy resins, beta-hydroxy(alkyl) amide resins, hydroxy (alkyl) urea resins, oxazoline, alkylatedcarbamate resins, (meth)acrylates, isocyanates, blocked isocyanates,polyacids, anhydrides, organometallic acid-functional materials,polyamines, polyamides, aminoplasts, aziridines, and combinationsthereof. The coating compositions of the present invention can also befree of additional film-forming resins and/or crosslinkers.

The crosslinking compositions can also comprise a colorant. As usedherein, “colorant” refers to any substance that imparts color and/orother opacity and/or other visual effect to the composition. Thecolorant can be added to the coating in any suitable form, such asdiscrete particles, dispersions, solutions, and/or flakes. A singlecolorant or a mixture of two or more colorants can be used in thecoatings of the present invention.

Example colorants include pigments (organic or inorganic), dyes andtints, such as those used in the paint industry and/or listed in the DryColor Manufacturers Association (DCMA), as well as special effectcompositions. A colorant may include, for example, a finely dividedsolid powder that is insoluble, but wettable, under the conditions ofuse. A colorant can be organic or inorganic and can be agglomerated ornon-agglomerated. Colorants can be incorporated into the coatings by useof a grind vehicle, such as an acrylic grind vehicle, the use of whichwill be familiar to one skilled in the art.

Example pigments and/or pigment compositions include, but are notlimited to, carbazole dioxazine crude pigment, azo, monoazo, diazo,naphthol AS, benzimidazolone, isoindolinone, isoindoline and polycyclicphthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole,thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanthrone,pyranthrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalonepigments, diketo pyrrolo pyrrole red (“DPPBO red”), titanium dioxide,carbon black, and mixtures thereof.

Example dyes include, but are not limited to, those that are solventand/or aqueous based such as phthalo green or blue, iron oxide, bismuthvanadate, anthraquinone, and perylene and quinacridone.

Example tints include, but are not limited to, pigments dispersed inwater-based or water miscible carriers such as AQUA-CHEM 896commercially available from Degussa, Inc., and CHARISMA COLORANTS andMAXITONER INDUSTRIAL COLORANTS commercially available from AccurateDispersions Division of Eastman Chemical, Inc.

The colorant which can be used with the crosslinking composition of thepresent invention can also comprise a special effect composition orpigment. As used herein, a “special effect composition or pigment”refers to a composition or pigment that interacts with visible light toprovide an appearance effect other than, or in addition to, a continuousunchanging color. Example special effect compositions and pigmentsinclude those that produce one or more appearance effects such asreflectance, pearlescence, metallic sheen, texture, phosphorescence,fluorescence, photochromism, photosensitivity, thermochromism,goniochromism, and/or color-change. Non-limiting examples of specialeffect compositions can include transparent coated mica and/or syntheticmica, coated silica, coated alumina, aluminum flakes, a transparentliquid crystal pigment, a liquid crystal coating, and combinationsthereof.

Other non-limiting examples of components that can be used with thecrosslinking composition of the present invention include plasticizers,abrasion resistant particles, fillers including, but not limited to,micas, talc, clays, and inorganic minerals, anti-oxidants, hinderedamine light stabilizers, UV light absorbers and stabilizers,surfactants, flow and surface control agents, thixotropic agents,organic cosolvents, reactive diluents, catalysts, reaction inhibitors,corrosion-inhibitors, and other customary auxiliaries.

The components that form the coating composition can also be combinedand/or mixed in a liquid medium. For example, the compound comprisingfunctional groups represented by Chemical Structure (I) and optionallyother components previously described can be combined and mixed in anon-aqueous or aqueous liquid medium.

As used herein, an “aqueous liquid medium” refers to a liquid mediumcomprising greater than 50 weight % water, based on the total weight ofthe liquid medium. Such aqueous liquid mediums can for example compriseat least 60 weight % water, or at least 70 weight % water, or at least80 weight % water, or at least 90 weight % water, or at least 95 weight% water, or 100 weight % water, based on the total weight of the liquidmedium. The solvents that, if present, make up less than 50 weight % ofthe liquid medium include organic solvents such as any of the organicsolvents previously described for example.

The crosslinking compositions of the present invention can be used as acoating composition. As used herein, a “coating composition” refers to acomposition that can form a coating over at least a portion of asubstrate. It is appreciated that the crosslinking composition of thepresent invention can be used as a coating composition in variousapplications and can be applied to a wide range of substrates known inthe coatings industry. For example, the coating composition of thepresent invention can be applied to automotive substrates and components(e.g. automotive vehicles including, but not limited to, cars, buses,trucks, trailers, etc.), industrial substrates, aircraft and aircraftcomponents, marine substrates and components such as ships, vessels, andon-shore and off-shore installations, storage tanks, windmills, nuclearplants, packaging substrates, wood flooring and furniture, apparel,electronics, including housings and circuit boards, glass andtransparencies, sports equipment, including golf balls, stadiums,buildings, bridges, and the like. These substrates can be, for example,metallic or non-metallic.

Metallic substrates include, but are not limited to, tin, steel(including electrogalvanized steel, cold rolled steel, hot-dippedgalvanized steel, steel alloys, or blasted/profiled steel, amongothers), aluminum, aluminum alloys, zinc-aluminum alloys, steel coatedwith a zinc-aluminum alloy, and aluminum plated steel. As used herein,blasted or profiled steel refers to steel that has been subjected toabrasive blasting and which involves mechanical cleaning by continuouslyimpacting the steel substrate with abrasive particles at high velocitiesusing compressed air or by centrifugal impellers. The abrasives aretypically recycled/reused materials and the process can efficientlyremoval mill scale and rust. The standard grades of cleanliness forabrasive blast cleaning is conducted in accordance with BS EN ISO8501-1.

Further, non-metallic substrates include polymeric and plasticsubstrates including polyester, polyolefin, polyamide, cellulosic,polystyrene, polyacrylic, poly(ethylene naphthalate), polypropylene,polyethylene, nylon, EVOH, polylactic acid, other “green” polymericsubstrates, poly(ethylene terephthalate) (PET), polycarbonate,polycarbonate acrylobutadiene styrene (PC/ABS), polyamide, wood, veneer,wood composite, particle board, medium density fiberboard, cement,stone, glass, paper, cardboard, textiles, leather, both synthetic andnatural, and the like. It is appreciated that the coating compositionscan be applied to various areas of any of the previously describedsubstrates to form a continuous solid coating such as over the body andedges of a substrate.

The coating composition of the present invention is particularlybeneficial when applied to a metallic substrate. For example, thecoatings of the present invention are particularly beneficial whenapplied to metallic substrates that are used to fabricate automotivevehicles, such as cars, trucks, and tractors.

The coating compositions of the present invention can be applied by anymeans standard in the art, such as electrocoating when used as anelectrodepositable coating composition, spraying, dipping, rolling,brushing, and the like. As used herein, an “electrodepositable coatingcomposition” refers to a composition that is capable of being depositedonto an electrically conductive substrate under the influence of anapplied electrical potential.

The coatings formed from the coating compositions of the presentinvention can be applied to a dry film thickness, for example, of from 5microns to 100 microns, or from 5 microns to 60 microns, or from 8microns to 40 microns, or from 8 microns to 20 microns.

Once applied to the substrate, the composition can be dehydrated andcured to form the coating layer. The coating composition can bedehydrated and cured at temperatures of 165° C. or less, or 160° C. orless, or 140° C. or less, or 120° C. or less, or 100° C. or less, or 80°C. or less. The coating composition can be dehydrated and cured atambient temperatures (e.g. 20° C.) to 165° C., or from ambienttemperatures to 140° C., or from ambient temperatures to 120° C., orfrom ambient temperatures to 100° C., or from ambient temperatures to80° C., or from 40° C. to 160° C., or from 40° C. to 140° C., or from40° C. to 120° C., or from 40° C. to 100° C., or from 40° C. to 80° C.The terms “curable”, “cure”, and the like, mean that at least a portionof the resinous materials in a composition is crosslinked orcrosslinkable.

The coating composition can be applied to a substrate to form amonocoat. As used herein, a “monocoat” refers to a single layer coatingsystem that is free of additional coating layers. Thus, the coatingcomposition can be applied directly to a substrate without anyintermediate coating layer and cured to form a single layer coating,i.e. a monocoat. The coating composition can also be applied directlyover a pretreated substrate as a monocoat. For example, the substratecan be pretreated with an iron phosphate treatment, zinc phosphatetreatment, zirconium treatment, titanium treatment, or silane treatment.

Alternatively, the coating composition can be applied to a substrate asat least one coating layer in a multi-layer coating. For instance, thecoating composition can be applied as a basecoat in a multi-layercoating. As used herein, a “basecoat” refers to a coating compositionfrom which a coating is deposited onto a primer and/or directly onto asubstrate, optionally, including components (such as pigments) thatimpact the color and/or provide other visual impact, and which may beovercoated with a protective and decorative topcoat. As used herein, a“primer” refers to a coating composition from which an undercoating maybe deposited onto a substrate in order to prepare the surface forapplication of a protective or decorative coating system.

It is appreciated that the multi-layer coating can comprise multiplecoating layers such as three or more, or four or more, or five or more,coating layers. For example, the previously described coatingcomposition of the present invention can be applied as a first basecoatover substrate or a primer layer, and additional coating layers can beapplied over the first basecoat layer as additional basecoats and/ortopcoats.

The additional coating layers can be formed from a coating compositionthat includes a film-forming resin that is the same or different fromeach other. The additional coating layers can be prepared with any ofthe film-forming resins, crosslinkers, colorants, and/or othercomponents previously described. Further, each coating composition canbe applied as a dry-on-dry process where each coating composition isdried or cured to form a coating layer prior to application of anothercomposition coating. Alternatively, all or certain combinations of eachcoating composition can be applied as a wet-on-wet process and dried orcured together.

It was found that coatings formed from the crosslinking compositions ofthe present invention can exhibit various desirable properties. Forinstance, coatings formed from the crosslinking compositions of thepresent invention can be formed at low dehydration/cure temperaturesand/or provide good solvent resistance, and which do not have some ofthe drawbacks and concerns associated with isocyanate functionalcompounds, such as the use of volatile leaving groups.

The present invention is also directed to the following aspects.

A first aspect is directed to a crosslinking composition comprising: acompound comprising at least two functional groups that are eachindependently represented by Chemical Structure (I):

X is an oxygen, sulfur, or nitrogen; R¹ is an alkyl group, an arylgroup, or an alkylaryl group; R², R³, and R⁴ are each independently analkyl group, an aryl group, an alkylaryl group, or a hydrogen; R⁵ is analkyl group, an aryl group, an alkylaryl group, or a hydrogen; z is 0when X is oxygen or sulfur and z is 1 when X is nitrogen; and when adouble bond is formed between a carbon atom bonded to R³ and an adjacentnitrogen, m is 0, and when a single bond is formed between the carbonatom bonded to R³ and the adjacent nitrogen, m is 1; and wherein: (i)the compound further comprises one or more additional functional groupsthat are reactive with the functional groups represented by ChemicalStructure (I) such that the compound is self-crosslinkable; and/or (ii)the composition further comprises a film-forming resin comprisingfunctional groups that are reactive with the functional groupsrepresented by Chemical Structure (I) of the compound.

A second aspect is directed to the crosslinking composition of the firstaspect, wherein X is an oxygen.

A third aspect is directed to the crosslinking composition of the firstor second aspect, wherein at least one of the functional groups ofChemical Structure (I) is represented by Chemical Structure (II):

A fourth aspect is directed to the crosslinking composition of any ofthe preceding aspects, wherein at least one of the functional groups ofChemical Structure (I) is represented by Chemical Structure (III):

A fifth aspect is directed to the crosslinking composition of any of thepreceding aspects, wherein (i) the compound further comprises the one ormore additional functional groups that are reactive with the functionalgroups represented by Chemical Structure (I) such that the compound isself-crosslinkable.

A sixth aspect is directed to the crosslinking composition of the fifthaspect, wherein the additional functional groups comprise hydroxylfunctional groups.

A seventh aspect is directed to the crosslinking composition of any ofthe preceding aspects, wherein the compound further comprises esterlinkages, ether linkages, aromatic groups, or a combination thereof.

An eighth aspect is directed to the crosslinking composition of any ofthe preceding aspects, wherein the compound is obtained from reactantscomprising: (i) a reaction product of: (a) a mono-aldo or ketofunctional compound comprising a hydroxyl functional group, an aminofunctional group, a carboxylic acid functional group, a thiol functionalgroup, or any combination thereof; and (b) a hydrazide or hydrazonecomprising a group represented by —XR¹(R⁵)_(z) that is attached to acarbon atom of the hydrazide or hydrazone, wherein R¹ is an alkyl group,an aryl group, or an alkylaryl group; X is an oxygen, sulfur, ornitrogen; R⁵ is an alkyl group, an aryl group, an alkylaryl group, or ahydrogen; z is 0 when X is oxygen or sulfur and z is 1 when X isnitrogen; and (ii) a component comprising two or more functional groupsreactive with the hydroxyl functional group, the amino functional group,the carboxylic acid functional group, and/or the thiol functional groupof the reaction product of (i).

A ninth aspect is directed to the crosslinking composition of the eighthaspect, wherein (i) (a) the mono-aldo or keto functional compoundcomprises a hydroxyl functional group and (ii) the component comprisestwo or more epoxy functional groups reactive with the hydroxylfunctional group of the reaction product of (i).

A tenth aspect is directed to the crosslinking composition of any one ofthe first through seventh aspects, wherein the compound is obtained fromreactants comprising: (i) a hydrazide or hydrazone comprising a grouprepresented by —XR¹(R⁵)_(z) that is attached to a carbon atom of thehydrazide or hydrazone, wherein R¹ is an alkyl group, an aryl group, oran alkylaryl group; X is an oxygen, sulfur, or nitrogen; R⁵ is an alkylgroup, an aryl group, an alkylaryl group, or a hydrogen; z is 0 when Xis oxygen or sulfur and z is 1 when X is nitrogen; and (ii) a componentcomprising two or more functional groups reactive with an amino group ofthe hydrazide or hydrazone of (i).

An eleventh aspect is directed to the crosslinking composition of thetenth aspect, wherein the two or more functional groups of component(ii) comprise ethylenically unsaturated functional groups, ketofunctional groups, aldo functional groups, epoxy functional groups, orany combination thereof that are reactive with the amino group of thehydrazide or hydrazone of (i).

A twelfth aspect is directed to the crosslinking composition of any ofthe preceding aspects, wherein the composition further comprises (ii)the film-forming resin comprising functional groups reactive with thefunctional groups represented by Chemical Structure (I) of the compound.

A thirteenth aspect is directed to the crosslinking composition of thetwelfth aspect, wherein the film-forming resin comprises hydroxylfunctional groups, amino functional groups, thiol functional groups, ora combination thereof.

A fourteenth aspect is directed to the crosslinking composition of thetwelfth or thirteenth aspect, wherein the film-forming resin has anequivalent weight of 400 or less.

A fifteenth aspect is directed to the crosslinking composition of any ofthe preceding aspects, wherein the crosslinking composition is a coatingcomposition that forms a coating when cured.

A sixteenth aspect is directed to the crosslinking composition of thefifteenth aspect, wherein the coating composition is anelectrodepositable coating composition.

A seventeenth aspect is directed to a substrate at least partiallycoated with the coating formed from the coating composition of thefifteenth or sixteenth aspect.

An eighteenth aspect is directed to the substrate of the seventeenthaspect, wherein the coating is formed directly over at least a portionof the substrate.

A nineteenth aspect is directed to the substrate of the seventeenthaspect, wherein the coating is formed over one or more additionalcoating layers formed over the substrate.

A twentieth aspect is directed to the substrate of any one of theseventeenth through nineteenth aspects, wherein one or more additionalcoating layers are formed over the coating.

The following examples are presented to demonstrate the generalprinciples of the invention. The invention should not be considered aslimited to the specific examples presented. All parts and percentages inthe examples are by weight unless otherwise indicated.

Example 1 Preparation of a Precursor

A precursor was prepared by charging 44.2 g hydroxyacetophenone, 29.28 gmethyl carbazate, and 162.5 g isopropanol into a 1 L flask with astirrer, a condenser, and a thermocouple under nitrogen blanket. Themixture was heated to reflux with a heating mantle and the reaction wasmonitored with TLC. Once the reaction was completed, isopropanol wasremoved with a Dean-Stark apparatus and 50 g xylene was added todisperse the precipitated solid. The mixture was stirred at 100° C. for30 min. The reaction was cooled and the precipitate was collected byfiltration. The precipitate was then washed with ethanol and dried toyield the product as an off-white solid. The resulting precursor wascharacterized as methyl2-(1-(4-hydroxyphenyl)ethylidene)hydrazine-1-carboxylate.

Example 2 Preparation of a Precursor

A precursor was prepared by charging 32.7 g hydroxyacetophenone, 25.0 gethyl carbazate, and 112.5 g isopropanol into a 1 L flask with astirrer, a condenser, and a thermocouple under nitrogen blanket. Themixture was heated to reflux with a heating mantle and the reaction wasmonitored with TLC. Once the reaction was completed, isopropanol wasremoved with a Dean-Stark apparatus and 50 g xylene was added todisperse the precipitated solid. The mixture was stirred at 100° C. for30 min. The reaction was cooled and the precipitate was collected byfiltration. The precipitate was then washed with ethanol and dried toyield the product as an off-white solid. The resulting precursor wascharacterized as ethyl2-(1-(4-hydroxyphenyl)ethylidene)hydrazine-1-carboxylate.

Example 3 Preparation of a Di-Functional Crosslinker

A di-functional crosslinker was prepared by 62.4 g of the precursor fromexample 1, 51.0 g Epon® 828 (difunctional bisphenol A/epichlorohydrinderived liquid epoxy, commercially available from Hexion), 7.65 gtrimethylamine, and 195 g ethanol were charged into a 1 L flask with astirrer, a condenser, and a thermocouple under nitrogen blanket. Thereaction was heated to reflux with a heating mantle and the reaction wasmonitored with TLC. Once the Epon® 828 starting material was gone fromTLC, the reaction was cooled down and filtered. The filtrate wasconcentrated with a rotary evaporator to yield the product as a crunchyyellow solid.

Example 4 Preparation of a Di-Functional Crosslinker

A di-functional crosslinker was prepared by charging 12.93 g of theprecursor from example 2, 10.88 g Epon™ 828 (difunctional bisphenolA/epichlorohydrin derived liquid epoxy, commercially available fromHexion), 1.63 g trimethylamine, and 83.2 g ethanol were charged into a500 mL flask with a stirrer, a condenser, and a thermocouple undernitrogen blanket. The reaction was heated to reflux with a heatingmantle and the reaction was monitored with TLC. Once the Epon™ 828starting material was gone from TLC, the reaction was cooled down andfiltered. The filtrate was concentrated with a rotary evaporator toyield the product as a crunchy yellow solid.

Example 5 Preparation of a Tri-Functional Crosslinker

A tri-functional crosslinker was prepared by charging 5.0 g of theprecursor from example 1, 2.38 g triglycidyl isocyanurate (TGIC), 0.5 gtrimethylamine, and 15.0 g ethanol into a 500 mL flask with a stirrer, acondenser, and a thermocouple under nitrogen blanket. The reaction washeated to reflux with a heating mantle and the reaction was monitoredwith TLC. Once the starting materials were gone from TLC, the reactionwas cooled down and filtered. The filtrate was concentrated with arotary evaporator to yield the product as a crunchy yellow solid.

Example 6 Preparation of a Di-Functional Crosslinker

A di-functional crosslinker was prepared by charging 10.0 gisophthalaldehyde, 19.71 g tert-butyl carbazate, and 130 g isopropanolinto a 500 mL flask with a stirrer, a condenser, and a thermocoupleunder nitrogen blanket. The reaction was heated to reflux with a heatingmantle and kept refluxing for 3 h. Solvent was removed with a Dean-Starkapparatus and 50 g xylene was added to disperse the precipitated solid.The mixture was stirred for 30 min at 100° C. The precipitate wasfiltered and washed with ethanol to yield the product as a white solid.The resulting crosslinker was characterized as di-tert-butyl2,2′-(1,3-phenylenebis(methaneylylidene))-bis(hydrazine-1-carboxylate).

Example 7 Preparation of a Di-Functional Crosslinker

A di-functional crosslinker was prepared by charging 40.50 g tert-butylcarbazate, 21.48 g of cyclohexanedicarboxaldehyde, and 141.86 g ofxylene into a 500 mL flask with a stirrer, a condenser, and athermocouple under nitrogen blanket. The reaction was subsequentlyheated to 100° C. with a heating mantle and stirred for 1 hour (a heatgun was periodically use to heat glassware and promote distillation ofwater to a Dean Stark trap). After cooling, the white solid was filteredand washed with xylene. The resulting crosslinker was characterized asdi-tert-butyl2,2′-(cyclohexane-1,3-diylbis(methaneylylidene))(2E,2′E)-bis(hydrazine-1-carboxylate).

Example 8 Preparation of a Tri-Functional Crosslinker

A tri-functional crosslinker was prepared by charging 10.74 g oftrimethylolpropane triacrylate, 14.34 g of tert-butyl carbazate, and70.00 g of Dowanol™ PM (glycol ether solvent, commercially availablefrom Dow) into a 500 mL flask with a stirrer, a condenser, and athermocouple under nitrogen blanket. The reaction was subsequentlystirred at ambient temperature for two days. Volatiles were removedunder reduced pressure on a rotary evaporator to yield a clear viscousliquid.

Example 9 Preparation of a Polymeric Crosslinker

A polymeric crosslinker was prepared by charging 261.17 g ofketo-functional acrylic polymer (solid %: 50% in Dowanol™ PM, glycolether solvent, commercially available from Dow) and 13.26 g ofmethylcarbazate into a 1 L flask with a stirrer, a condenser, and athermocouple under nitrogen blanket. The reaction was heated to refluxwith a heating mantle and the reaction was monitored with ¹³C-NMR. Onceketone ¹³C-NMR peak was gone from NMR, the reaction was cooled down andpoured out to yield the product as a yellow liquid.

Example 10 Preparation of a Polymeric Crosslinker

A polymeric crosslinker was prepared by charging 35.1 g of the precursorfrom example 1, 71.4 g epoxy-functional acrylic polymer [solid %: 63.3%in butylcellosolve-n-butanol (3:1)], 50 g butylcellosolve-n-butanol(3:1), and 0.3 g ethyltriphenylphosphonium iodide into a 1 L flask witha stirrer, a condenser, and a thermocouple under nitrogen blanket. Thereaction was heated to reflux with a heating mantle and the reaction wasmonitored with titration. Once epoxy equivalent weight becameundetectable, the reaction was cooled down and poured out to yield theproduct as a yellow liquid.

Example 11 Preparation of a Polymeric Crosslinker

A polymeric crosslinker was prepared by charging 24.6 g of levulinicacid, 97.58 g epoxy-functional acrylic polymer [solid %: 63.3% inbutylcellosolve-n-butanol (3:1)], 55 g butylcellosolve-n-butanol (3:1),and 0.4 g ethyltriphenylphosphonium iodide into a 1 L flask with astirrer, a condenser, and a thermocouple under nitrogen blanket. Thereaction was heated to reflux with a heating mantle and the reaction wasmonitored with titration. Once epoxy equivalent weight becameundetectable, the reaction was cooled down. Then 19.27 g methylcarbazatewas added to the flask and heated back to 105° C. The reaction wasmonitored with ¹³C-NMR. Once the ketone ¹³C-NMR peak was gone from NMR,the reaction was cooled down and poured out to yield the product as ayellow liquid.

Example 12 Preparation of Coating Compositions and Coatings FormedTherefrom

Various coating compositions were prepared by mixing a hydroxylfunctional acrylic resin with each of the crosslinkers of examples of3-6 and 9-11 at a 1:1 equivalence ratio based on hydroxyl content of theacrylic resin. Next, the coating compositions were drawn down over 4inches by 12 inches steel panels that were pre-coated with an ED 6465electrocoat (an electrocoat commercially available from PPG) using adrawdown bar. The panels with wet films were flashed at ambientconditions for 5 minutes before being baked for 30 minutes at 80° C.,120° C., 140° C., and 160° C. in an oven. After bake, the panels weretaken out of the oven and cooled down to room temperature. The dry filmthickness was around 50-60 um.

For examples 7 and 8, the hydroxyl functional acrylic resin and solventwere charged into a 2 ounce jar, then mixed with a tongue depressoruntil the mixture was homogeneous. The crosslinkers were subsequentlyadded to the jar (30% on non-volatile weight) and mixed until ahomogeneous mixture was obtained. A thin line of the jar contents werethen poured onto a CRS (cold rolled steel) C700 panel (not pre-coated)with 6″×8″ dimensions. The contents were drawn down onto the C700 panelusing a steel grated rod to yield a thickness of ˜1 mil on the panel.The panel was then placed into a convection oven at a set temperaturefor one hour. Once the hour was complete, the panel was removed from theoven and cooled to room temperature.

Example 13 Evaluation of Coatings

The coatings formed in example 12 using the crosslinkers of examples 3,5, and 9-11 were tested for solvent resistance. Solvent resistance wastested using Wypall brand 03086 wipes (commercially available atKimberly-Clark Professional Inc.) and a modified method of ASTM D5402-06 according to the following procedure: one 8 inch by 1 inch areaon the coated surface to test was marked; one piece of wipe was foldedinto a double thickness and saturated to a dripping wet condition withmethyl ethyl ketone (MEK) solvent; an index finger was placed into thecenter of the folded wipe and the test area was rubbed at a 45° angle inwhich one forward and back motion was considered one double rub;repositioning the index finger on unused portions of the folded wipe andrub the test area with additional double rubs; and re-saturate the wipeevery 25 double rubs. This procedure was repeated until there was avisible scratch/mar on the film.

For the coatings formed in example 12 using the crosslinkers of examples7 and 8, solvent resistance was evaluated with acetone in which a testarea was rubbed in a forward and backward motion horizontally along thepanel with a double folded Wypall X80 wipe damped with acetone, the testarea. For every 25 rubs, the wipe was damped once more with acetonesolvent. Rubbing was continued until 100 rubs were counted or a visiblescratch/mar in the system was observed.

The results of the solvent resistance testing are shown in Table 1.

TABLE 1 Composition used to form Coating Double rubs Example 3 at 120°C. bake 50 Example 3 at 140° C. bake >100 Example 5 at 80° C. bake 30Example 5 at 120° C. bake 60 Example 5 at 140° C. bake >100 Example 7 at160° C. bake >100 Example 8 at 160° C. bake 85 Example 9 at 140° C. bake40 Example 10 at 140° C. bake >100 Example 11 at 140° C. bake >100

As shown in Table 1, the coatings formed from the compositions of thepresent invention comprising the compound having functional groupsrepresented by the previously described Chemical Structure (I) exhibitedgood to excellent solvent resistance at various cure temperatures.

The rheology curves (phase angle) of the coatings formed in Example 12using the crosslinkers of examples 3-6 were also evaluated. An AntonPaar MCR 301 instrument was used for the analysis. A 600 μL samplevolume was placed on the instrument and a temperature ramp was runstarting at 25° C. (10° C. ramps were held for 3 minutes). The programstops when the sample has reached a phase angle of 10°. Reaching a phaseangle of 10° is associated with cure of the sample. The rheology curves(phase angle) are shown in Table 2.

TABLE 2 Composition used Temperature of phase to form Coating shift at10° angle Example 3 150° C. Example 4 120° C. Example 5  80° C. Example6 130° C.

As shown in Table 2, the coatings of the present invention can provide10° angle phase shifts at low temperatures.

Example 14 Preparation and Evaluation of a Coating Formed with aSelf-Crosslinkable System

A coating composition was prepared using the compound of Example 5without additional resins such that the compound of Example 5crosslinked with itself to form the coating. The coating composition wasdrawn down over 4 inch by 12 inch steel panels that were pre-coated withan ED 6465 electrocoat (an electrocoat commercially available from PPG)using a drawdown bar. The panels with wet films were flashed at ambientconditions for 5 minutes before being baked for 30 minutes at 80° C. and140° C. in an oven. After bake, the panels were taken out of the ovenand cooled down to room temperature. The dry film thickness was around50-60 um.

The coatings were then tested for solvent resistance according toExample 13. The results of the solvent resistance testing are shown inTable 3.

TABLE 3 Bake Temperature Double rubs 80° C. bake >100 140° C. bake >100

As shown in Table 3, the coatings formed from the compositions of thepresent invention comprising the compound of Example 5 as aself-crosslinkable system exhibited excellent solvent resistance atvarious cure temperatures.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

The invention claimed is:
 1. A crosslinking composition comprising: acompound comprising at least two functional groups that are eachindependently represented by Chemical Structure (I):

X is an oxygen, sulfur, or nitrogen; R¹ is an alkyl group, an arylgroup, or an alkylaryl group; R², R³, and R⁴ are each independently analkyl group, an aryl group, an alkylaryl group, or a hydrogen; and R⁵ isan alkyl group, an aryl group, an alkylaryl group, or a hydrogen; z is 0when X is oxygen or sulfur and z is 1 when X is nitrogen; when a doublebond is formed between a carbon atom bonded to R³ and an adjacentnitrogen, m is 0, and when a single bond is formed between the carbonatom bonded to R³ and the adjacent nitrogen, m is 1; and wherein: (i)the compound further comprises one or more additional functional groupsthat are reactive with the functional groups represented by ChemicalStructure (I) such that the compound is self-crosslinkable; and/or (ii)the composition further comprises a film-forming resin comprisingfunctional groups that are reactive with the functional groupsrepresented by Chemical Structure (I) of the compound.
 2. Thecrosslinking composition of claim 1, wherein X is an oxygen.
 3. Thecrosslinking composition of claim 1, wherein at least one of thefunctional groups of Chemical Structure (I) is represented by ChemicalStructure (II):


4. The crosslinking composition of claim 1, wherein at least one of thefunctional groups of Chemical Structure (I) is represented by ChemicalStructure (III):


5. The crosslinking composition of claim 1, wherein (i) the compoundfurther comprises the one or more additional functional groups that arereactive with the functional groups represented by Chemical Structure(I) such that the compound is self-crosslinkable.
 6. The crosslinkingcomposition of claim 5, wherein the additional functional groupscomprise hydroxyl functional groups.
 7. The crosslinking composition ofclaim 1, wherein the compound further comprises ester linkages, etherlinkages, aromatic groups, or a combination thereof.
 8. The crosslinkingcomposition of claim 1, wherein the compound is obtained from reactantscomprising: (i) a reaction product of: (a) a mono-aldo or ketofunctional compound comprising a hydroxyl functional group, an aminofunctional group, a carboxylic acid functional group, a thiol functionalgroup, or any combination thereof; and (b) a hydrazide or hydrazonecomprising a group represented by —XR¹(R⁵)_(z) that is attached to acarbon atom of the hydrazide or hydrazone, wherein R¹ is an alkyl group,an aryl group, or an alkylaryl group; X is an oxygen, sulfur, ornitrogen; R⁵ is an alkyl group, an aryl group, an alkylaryl group, or ahydrogen; z is 0 when X is oxygen or sulfur and z is 1 when X isnitrogen; and (ii) a component comprising two or more functional groupsreactive with the hydroxyl functional group, the amino functional group,the carboxylic acid functional group, and/or the thiol functional groupof the reaction product of (i).
 9. The crosslinking composition of claim8, wherein (i) (a) the mono-aldo or keto functional compound comprises ahydroxyl functional group and (ii) the component comprises two or moreepoxy functional groups reactive with the hydroxyl functional group ofthe reaction product of (i).
 10. The crosslinking composition of claim1, wherein the compound is obtained from reactants comprising: (i) ahydrazide or hydrazone comprising a group represented by —XR¹(R⁵)_(z)that is attached to a carbon atom of the hydrazide or hydrazone, whereinR¹ is an alkyl group, an aryl group, or an alkylaryl group; X is anoxygen, sulfur, or nitrogen; R⁵ is an alkyl group, an aryl group, analkylaryl group, or a hydrogen; z is 0 when X is oxygen or sulfur and zis 1 when X is nitrogen; and (ii) a component comprising two or morefunctional groups reactive with an amino group of the hydrazide orhydrazone of (i).
 11. The crosslinking composition of claim 10, whereinthe two or more functional groups of component (ii) compriseethylenically unsaturated functional groups, keto functional groups,aldo functional groups, epoxy functional groups, or any combinationthereof that are reactive with the amino group of the hydrazide orhydrazone of (i).
 12. The crosslinking composition of claim 1, whereinthe composition further comprises (ii) the film-forming resin comprisingfunctional groups reactive with the functional groups represented byChemical Structure (I) of the compound.
 13. The crosslinking compositionof claim 12, wherein the film-forming resin comprises hydroxylfunctional groups, amino functional groups, thiol functional groups, ora combination thereof.
 14. The crosslinking composition of claim 13,wherein the film-forming resin has an equivalent weight of 400 or less.15. The crosslinking composition of claim 1, wherein the crosslinkingcomposition is a coating composition that forms a coating when cured.16. The crosslinking composition of claim 15, wherein the coatingcomposition is an electrodepositable coating composition.
 17. Asubstrate at least partially coated with the coating formed from thecoating composition of claim
 15. 18. The substrate of claim 17, whereinthe coating is formed directly over at least a portion of the substrate.19. The substrate of claim 17, wherein the coating is formed over one ormore additional coating layers formed over the substrate.
 20. Thesubstrate of claim 17, wherein one or more additional coating layers areformed over the coating formed from the coating composition of claim 15.